This is a temporary issue that will be fixed in an upcoming version of the mobile app.
Google recently changed their policy on what types of apps they will allow for "single sign on" (signing in with your Google account). Unfortunately this means we need to rebuild the mobile app so it complies with this new policy. This is already in the works and will be released soon.
If you have created your account by signing in with your Google account and need to sign in with the same account on the mobile app, you can click the "reset your password" link and create a unique password using the same email address. This will allow you to log in with a unique password and access the same account.